&#34;lith&#34; developers containing water soluble block polymers of polyoxypropylene and polyoxyethylene



United States Patent LITH DEVELOPERS CONTAINING WATER 50L- UBLE BLOCK POLYMERS OF POLYOXYPROPYL- ENE AND PGLYUXYETHYLENE Lewis T. Connolly and Thomas C. Montrois, Rochester, N.Y., assignors to Eastman Kodak Company, Rochester, N.Y., a corporation of New Jersey No Drawing. Filed Dec. 17, 1963, Ser. No. 331,108

19 Claims. (CI. 9666) This invention relates to photography and particularly to very high contrast stable developer compositions and their use in developing photographic light-sensitive elements.

Photographic films used in the graphic arts for making half-tone or line images should be capable of producing extremely high contrast and good image sharpness. These factors contribute in the case of half-tone images to high dot quality, that is, to the production of halftone dots of high density and sharpness. The photographic elements of the lith-type, that is, elements that have a fine grain high contrast silver halide emulsion containing at least 60 mole percent chloride, less than 40 mole percent bromide and less than about 5 mole percent iodide, require the use of pure hydroquinone developer solutions having very low free sulfite ion concentration in the alkaline solution in order to produce the high contrast and high dot quality required for good quality half-tone reproduction.

It is therefore an object of our invention to provide a composition useful for the preparation of a lith-type developer, said composition containing a block polymer of polyoxypropylene and polyoxyethylene that is valuable for developing high contrast images having high dot quality in lith-type elements. Another object is to provide a stable two solution concentrate useful for preparing a lith-type developer solution, one concentrate solution of which comprises a block polymer of polyoxypropylene and polyoxyethylene, and a p-dihydroxybenzene silver halide developing agent, and the other concentrate solution comprises a solution of an alkali, such that the said concentrates are diluted with water and combined to produce the working lith developer solution. Still another object is to provide a process for developing high contrast images having high dot quality in lith elements with our lith developers. Still other objects will be apparent from the following specification and claims.

These and other objects are accomplished according to our invention by use of our compositions comprising a water-soluble block polymer of polyoxypropylene and polyoxyethylene, a p-dihydroxybenzene silver halide developing agent, and an alkali metal sulfite, for preparing lith developer solutions that are valuable for developing high contrast images of high dot quality in lith elements. The water-soluble block polymers used to advantage according to our invention include those in which the polyoxypropylene chain (or moiety) has an average molecular weight between 800 to 2,100 and in which the polyoxyethylene units constitute from about to about 60 percent by weight of the block polymer. Developer solutions made according to our invention should contain at least 0.5 gram of free sulfite per liter of solution. However, larger amounts, as high as 10-40 gram per liter can be used. Also carbonyl bisuhite buffers can be used to advantage. All of our developer solutions are characterized by producing in lith emulsions, images having high contrast and high dot quality.

The water-soluble block polymers of polyoxypropylene and polyoxyethylene used to advantage according to our invention include those represented by the formula:

ice

wherein Y represents an organic radical having a valence of x, said radical being the residue 'of an organic com pound containing atoms selected from the class consisting of carbon, hydrogen, oxygen, nitrogen and sulfur with x active hydrogen atoms, such as, the residue of polyhydroxy compounds, e.g., ethylene glycol, 1,2-propanediol, 1,5-pentanediol, 1,2,3-propanetriol, sucrose, etc., the residue of a polybasic 'acid, e.g., oxalic acid, malonic acid, succinic acid, maleic acid, citric acid, etc., the residue of a polyamine, e.g., ethylenediamine, 1,3-diaminopropylene, etc., the residue of a polyamide, e.g., malonamide, succinamide, etc., the residue of a polythiol, e.g., 1,2-ethylenedithiol, 1,3-propylenedithiol, etc., etc.; it is an integer greater than 1; x is an integer greater than 1, so that the values of n and x are such that the molecular weight of the said polymer exclusive of Y, E and R is between 800 and 2,100; E represents a polyoxyethylene chain constituting from about 10 to about 60 percent by weight of said block polymer; and R represents the hydrogen atom, an alkyl group having from 1 to 20 carbon atoms (such as methyl, propyl, decyl, dodecyl, octadecyl, etc.), an alkylcarbonyl group in which the alkyl group has from 1 to 20 carbon atoms as described above, or an arylcarbonyl group, such as, benzoyl, p-methylbenzoyl, etc., etc.

Included among the preferred block polymers are those having the formula:

in which 12 represents an integer of from 14 to 36; a and c are each integers such that the sum of a+c has a total of from 4 to and the polyoxyethylene groups constitute between 10 and 60 percent by weight of the block polymer.

The block polymers of Formula II and of Formula I where R represents the hydrogen atom are described in Lundsted US. Patent 2,674,619, issued April 6, 1954. The block polymers of Formula I in which R is hydrogen are readily converted to compounds where R represents an organic residue by well known reactions using appropriate reagents and preferably conducted in a suitable inert organic solvent that is anhydrous. For example, alkyl halides, such as, alkyl chlorides, (e.g., methyl chloride, decyl chloride, etc.), alkyl bromides (e. g., ethylbromide, butyl bromide, etc.), alkyl-p-toluene sulfonates (e.g., methyl-p-toluene sulfonate, propyl-p-toluene sulfonate, etc.), etc., are used to advantage to prepare the compounds of Formula I in which R is an alkyl group from those in which R is hydrogen. The appropriate acid halide (e.g., acetyl chloride, propionyl chloride, stearoyl chloride, benzoyl chloride, acetyl bromide, benzoyl bromide, etc.) or the appropriate acid anhydride (e.g., acetic anhydride, etc.) are used to advantage to prepare 'block polymers of Formula I in which R represents an alkylcarbonyl group or an arylcarbonyl group.

The quality of the silver images produced in lithtype emulsion layers is conveniently measured in terms of contrast (i.e., 'y) and dot quality. Photographic image contrast is the slope of the straight line portion of a graph of optical density of the image vs. log of exposure. Dot quality is evaluated by observing the density and the edge sharpness of the individual dots in the developed half-tone negative under high magnification. Quality may be evaluated in highlight, shadow, and middle tone areas. Highlights in a half-tone negative consist of small clear openings covering about 10% of the area in a very dense surround. Shadow areas contain small dense dots covering about 10% of the clear area. Intermediate between these two extremes are areas of varying size, with 50% dots occurring in the middle; i.e.; 50% clear,

50% density. Quality is expressed in a progressive scale where is excellent and 1 is extremely poor. Dot quality below 6 is generally not acceptable.

Included among the water-soluble block polymers used to advantage according to our invention are the following typical polymers used for illustrative purposes.

Block Average Value Percent Polyoxy- Polymer Y is Derived of 11 in Formula ethylene by Weight N o. from I of Block Polymer Ethylenediamina. 9-17 40-49 do 26-34 40-49 Block polymers 1 through 7 are available commercially under the trade names Pluronic L61, L62, L44, L65, L64, L35 and P46 respectively, while our block polymers 8 and 9 are available under the trade name Tetronic 304 and 504 respectively.

The block polymers used according to our invention are water-soluble and can be used to advantage up to their solubility limits. A useful range of concentrations of the block polymer is from about 0.001 to about 0.1 g./l. of developer solution. A preferred concentration is about 0.01 g./l. The optimum concentration for a given block polymer will depend upon the particular results desired, the developer solution, the lith element, etc., and is readily determined by methods well known in the art.

The developing agents used to advantage in our lith developer compositions are p-dihydroxybenzene compounds, such as, hydroquinone, tolyl hydroquinone, chlorohydroquinone, etc. The developer compositions are substantially free of auxiliary developing agents, that is, contain no more than .05 g./l. of an auxiliary developing agent.

The developer compositions may contain as the alkali, any of the conventional alkaline materials such as alkali metal hydroxides (e.g., sodium hydroxide, potassium hydroxide, lithium hydroxide, etc.), alkali metal carbonates (e.g., sodium carbonate, potassium carbonate, etc.), alkali metal bicarbonates (e.g., sodium bicarbonate, potassium bicarbonate, etc.), alkali metal metaborates such as sodium metaborate, etc., etc.

The developer compositions contain alkali metal sulfite (e.g., sodium sulfite, potassium sulfite, etc.) either with or without an alkali metal bisulfite. In addition to the indicated free sulfite it may be desirable to include an alkali metal carbonyl bisulfite buffer in which the carbonyl moiety may be formaldehyde, acetaldehyde, acetone, etc., and the buffer may be an alkali metal formaldehyde bisulfite, alkali metal acetaldehyde bisulfite, alkali metal acetone bisulfite, etc.

Any of the other materials used in developer compositions such as alkali metal bromide boric acid, water softeners, such as, sodium hexametaphosphate, etc., may be used to advantage in my li-th developer.

Our working developer solutions are either prepared as needed by dissolving the appropriate amounts of the needed chemicals in water or preferably are prepared as concentrates that can -be stored until needed. Working developer solutions are conveniently and quickly prepared by diluting the concentrate with the appropriate amount of water which may be up to three times the volume of the concentrate depending upon the composition of the particular concentrate.

Typical compositions of our invention that are useful 'for the preparation of lith developers are illustrated by the following tables:

The working developer solution is prepared by adding the appropriate amount of water to concentrate Part A and to concentrate Part B and then combining the two solutions so that the resulting mixture contains the working solution concentrations for the various ingredients. For example, if both Part A and Part B (of the concentrate) contain the lowest indicated amount of each ingredient (e.g., 30 g. of hydroquinone, etc., etc.) then simply combining equal portions of Part A and Part B (say 500 cc. of each) will give 1 liter of the working solution having the indicated composition. However, if the highest indicated amount of each ingredient is used in each part of the concentrate (e.g., g. of hydroquinone, etc., etc.), then the combined parts A and B (2 liters total) will have to be diluted by adding 6 liters of water to give 8 liters of working solution having the concentrations given in the table.

The following table illustrates a typical monoconcentrate.

The working developer is prepared from a concentrate having the lowest indicated amount of each ingredient (e.g. 30 g. of hydroquinone, etc.), by adding an equal volume of water, however if the highest indicated amount of each ingredient is used in the concentrate, then two volumes of water must be added for each volume of concentrate to produce the concentration indicated for the working solution.

It is to be understood that other concentrates can be made according to our invention by including other ingredients that would be used to advantage by other working developer solutions. For example, other alkali metal salts, e.g. sodium carbonate, sodium sulfite, etc. may be used as well as other types of addenda as described previously. Also the concentrations of the ingredients can be varied in the working solution. Obviously the composition of the concentrates would be adjusted accordingly.

Any lith-type photographic element containing at least 60 mole percent chloride in the silver halide (emulsion) may be developed to advantage in my lith developer solution. MacWilliam US. Patent 2,756,148, issued July 24, 1956, for example, describes the preparation of typical lith elements that are used to advantage with our developer.

The following examples will still further illustrate our lnvention.

Example 1 A high contrast lith type film was exposed to a 133 line contact screen and a .10 log E step tablet. Two

Example 4 Pieces of lith film exposed as in Example 1 were processed in the following formula:

inch strips of this sheet were developed :for varying times 5 yq q l g-- in a lith developer having the following composition: Bonc acld Potassium sulfite g Potassium carbonate g 90 Hyqmqumone Potassium bromide g 2.7 Sod1um formaldehyde brsulfite 50.0 Dieth 1 1 1 y ene g yco cc Sod1um carbonate 39.0 1 Water toll Sodium bicarbonate 22.5 Sodi lfit 2,5 A second piece of film was processed in a similar develp t i b id 0,75 oper to which block polymer No. 3 was added at .01 gram W t to k 1,01 per liter. The data below show the improvement in dot 15 quality produced by the addition of our block polymer.

Without Additive With Additive Time Time High- 50% Shadow Speed H h- 50% Shad. Spd.

light light then fixed in a conventional alkali metal thiosulfate fiX- The above data show that our developer containing the ing bath, washed and dried. block polymer developed images in lith film having ex- A similar exposure was made on another piece of film cellent dot quality, while the developer containing no which was developed using the same technique as above, block polymer produced images having very inferior dot except .01 g./l. of block polymer No. 3 was added. 30 quality.

The table below shows the dot quality measured by Our lith type developers are characterized from other subjective evaluation of the dots for five different delith developers by containing certain water-soluble and velopment times. On the rating scale, 10 is the best gelatin dilfusible block polymers of polyoxypropylene and rating with decreasing quality indicated by lower numpolyoxyethylene. The presence of our block polymers in hers. our lith developers makes them valuable for developing high contrast images of high dot quality in lith type emulsion layers. It is unexpected that developers conwithout B1001; with mpolymer taining our block polymers would have these valuable Dev Time High Polymer 3 properties because the same developer contarning closely lights 40 related block polymers of polyoxypropylene and polyoxy- 50% Shadows High- 50% d. ethylene that are outside our invention do not produce any lights significant improvement in the developed image. 7 7 7 7% 8 7 Although the invention has been described in consid- 7% 7% 7 9 8% 8 erable detail with reference to certain preferred embodi- E g 2 3 ments thereof, it will be understood that variations and 6 s a 8 9 2 modifications can be effected without departing from the spirit and scope of the invention as described hereinabove and as defined in the appended claims. Example 2 We claim:

1. A composition useful for preparing a lith devel- Example 1 was repeated but comparing the developer oper solution, said composition comprising: without a block polymer with separate portions of the (1) a p-dihydroxybenzene silver halide developing developer to which 0.01 gram of our block polymers agent;

5, 6 and 7, and a block polymer outside our invention (2) an alkali metal sulfite; and a was added per liter of the solution. The block polymer (3) a water-soluble block polymer of polyoxyprooutside our invention had a block of polyoxypropylene pylene and polyoxyethylene in which the polyoxyhaving an average molecular Weight of 2750 and had propylene chain has an average molecular weight bepolyoxyethylene units constituting 80 percent of the block tween 800 and 2,100, and the polyoxyethylene units polymer. In each instance the developer containing our constitute from about 10 to about percent by block polymers 5, 6 and 7 produced improved dot quality weight of said block polymer. 1 compared to the developer without our block polymer, 60 2. A composition useful for preparing a lith devel- While the developer containing the block polymer outside oper solution, said composition comprising: our invention produced no significant improvement in dot (1) a p-dihydroxybenzene silver halide developing quality. agent;

Example 3 2) an alkali metal sulfite; and

(3) a Water-soluble block polymer having the formula:

Example 1 was repeated but comparing the developer without a block polymer with separate portions of the Y[(C3HGO)H E R]X developer to which gram of block P y 8 wherein Y represents an organic radical having a and No. 9 were added. The developers containing our v len f n is an integer greater than 1; x is an block polymers developed images that were improved integer greater than 1, so that the values of n and x over the images developed with the developer containing r u h th t the mole ular Weight of the said no polymer. polymer exclusive of Y, E and R is between 800 Similarly it can be shown that other block polymers are and 2,100; B represents a polyoxyethylene chain conused to advantage according to our invention to develop stituting from about 10 to about 60 percent by weight improved quality images in lith elements. of said polymer; and R is a member selected from the class consisting of the hydrogen atom, an alkyl group, an alkyl carbonyl group, and an aryl carbonyl group. 3. A composition of claim 1 in which the water-soluble block polymer has the formula:

wherein b represents an integer of from between 14 to 36; and a and c each represent integers such that the sum of represents an integer of from 4 to 80 and the polyoxyethylene groups constitute between and 60 percent by weight of said polymer.

4. A composition of claim 1 in which the molecular weight of the polyoxypropylene of the water-soluble block polymer is 750 and the polyoxyethylene groups constitute 40 percent by weight of the said block polymer.

5. A composition of claim 1 in which the molecular Weight of the polyoxypropylene of the water-soluble block polymer is 1200 and the polyoxyethylene groups constitute 60 percent by weight of the said block polymer.

6. A composition of claim 1 in which the molecular weight of the polyoxypropylene of the water-soluble block polymer is 1200 and the polyoxyethylene groups constitute 40 percent by weight of said block polymer.

7. A composition of claim 1 in which the molecular weight of the polyoxypropylene of the water-soluble block polymer is 1750 and the polyoxyethylene groups constitute 40 percent by weight of said block polymer.

8. A composition of claim 1 in which the molecular weight of the polyoxypropylene of the water-soluble block polymer is 950 and the polyoxyethylene groups constitute 50 percent by weight of said block polymer.

9. A composition of claim 1 containing from about 10 to about 40 grams of an alkali metal sulfite, said composition containing substantially no carbonyl bisulfitc buffer.

10. A composition of claim 1 containing less than about 10 grams of an alkali metal sulfite land a carbonyl bisulfite.

11. A photographic lith" developer prepared from the composition of claim 1, said developer containing an alkali and being substantially free of an auxiliary silver halide developing agent.

12. The process for forming a high contrast image in an image exposed photographic lithographic element comprising the step of contacting said element with an aqueous developer solution comprising:

(1) an alkali;

(2) a p-dihydroxybenzene silver halide developing agent;

(3) an alkali metal sulfite; and

(4) a water-soluble block polymer of polyoxypropylene in which the polyoxypropylene chain has an average molecular Weight between 800 and 2,100, and the polyoxyethylene units constitute from about '10 to about 60 percent by weight of said block polymer until a silver image is formed.

13. The process of claim 12 in which the block polymer has the formula:

wherein Y represents an organic radical having a valence of x; n is an integer greater than 1; x is an integer greater than 1, so that the values of n and x are such that the molecular weight of the said polymer exclusive of Y, E and R is between 800 and 2,100; E represents a polyoxyethylene chain constituting from about 10 to about percent by weight of said polymer; and R is a member selected from the class consisting of the hydrogen atom, an alkyl group, an alkyl carbonyl group, and an aryl carbonyl group.

14. The process of claim 12 in which the block polymer has the formula:

wherein b represents an integer of from between 14 to 36; and a and 0 each represent integers such that the sum of a+c represents an integer of from 4 to and the polyoxyethylene groups constitute between 10 and 60 percent by weight of said polymer.

15. The process of claim 12 in which the block polymer has a molecular weight of 750 and the polyoxyethylene groups constitute 40 percent by weight of the said block polymer.

16. The process of claim 12 in which the block polymer has a molecular weight of 1200 and the polyoxyethylene groups constitute 60 percent by weight of the said block polymer.

17. The process of claim 12 in which the block polymer has a molecular weight of 1200 and the polyoxyethylene groups constitute 40 percent by weight of said block polymer.

18. The process of claim 12 in which the block polymer has a molecular weight of 1750 and the polyoxyethylene groups constitute 40 percent by weight of said block polymer.

19. The process of claim 12 in which the block polymer has a molecular weight of 950 and the polyoxyethylene groups constitute 50 percent by weight of said block polymer.

References Cited by the Examiner UNITED STATES PATENTS 3,022,335 2/1962 Lundsted 252-351 X 3,084,044 4/1963 Dersch et al. 9666 3,193,386 7/1965 White 9667 X OTHER REFERENCES Churayeva et al.: Zh. Nauch. Prikl. Fot. Kine. 6, 139- 40 (No. 2, 1961); Translation in Ansco Abstracts, vol. 21, page 421, 4-62.

NORMAN G. TORCHIN, Primary Examiner.

C. E. DAVIS, Assistant Examiner.

ew UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3, 7 Dated September 1 2 H966 Inventofls) Lewi s Connolly and ThOmaS C. Montr'ois It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 7, line E L, between the expression, "pylene" and "in",

insert --and polyoXyethylene--.

(SEAL) Attest:

unemhmhmum E. S-OHUYLER, JR. g Omissioner of Patents 

12. THE PROCESS FOR FORMING A HIGH CONTRAST IMAGE IN AN IMAGE EXPOSED PHOTOGRAPHIC LITHOGRAPHIC ELEMENT COMPRISING THE STEP OF CONTRACTING SAID ELEMENT WITH AN AQUEOUS DEVELOPER SOLUTION COMPRISING: (1) AN ALKALI; (2) A P-DIHYDROXYBENZENE SILVER HALIDE DEVELOPING AGENT; (3) AN ALKALI METAL SULFITE; AND (4) A WATER-SOLUBLE BLOCK POLYMER OF POLYOXPROPYLENE IN WHICH THE POLYOXYPROPLENE CHAIN HAS AN AVERAGE MOLECULAR WEIGHT BETWEEN 800 AND 2,100, AND THE POLYOXYETHYLENE UNITS CONSTITUTE FROM ABOUT 10 TO ABOUT 60 PERCENT BY WEIGHT OF SAID BLOCK POLYMER UNIT A SILVER IMAGE IS FORMED. 